This invention provides a novel method for the manufacture of tungsten carbide grit. Tungsten carbide grit is well known for use in hardfacing applications such as on rotary rock bits and tool joint connections that are used primarily in well drilling where tools must withstand severe abrasion and the stresses of high impacts. In the prior art, grits have been made by crushing and screening tungsten carbide compositions. This method produced sharp faceted, irregularly shaped particles with inferior wear resistance. In U.S. Pat. No. 3,385,683 it was recognized that the irregularly shaped grit obtained by crushing tungsten carbide compositions were subject to wear problems because of the points and pressures on the grits and the lack of uniformity in the grit particles. This patent teaches a method for preparing tungsten carbide powders whereby spheres, cylinders, ovoids or cubes of tungsten carbide can be obtained for use as hardfacing on tools. A disclosure of the use of a tumbling procedure is mentioned for the production of tungsten carbide grit but no mention is made as to how this procedure is to be carried out.
It has been discovered that if tungsten carbide powder is combined with a suitable organic binder and agglomerated into particles which are sintered to remove the binder and form a tungsten carbide grit, a grit with blunt, round particles is obtained. These blunt tungsten carbide grits are obtained in good yield with a minimum of unuseable fine material. The blunt tungsten carbide grit has superior wear resistance properties as compared to the tungsten carbide grit obtained by crushing tungsten carbide blocks or compacts.